``spooky'' thumbnails in audio (ogg) files

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martinsteffen
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``spooky'' thumbnails in audio (ogg) files

Postby martinsteffen » 28 Apr 2017 17:54

My question is not really "trouble shooting" in that I don't have "troubles". But since quite some time I am wondering about: where do
the thumbnails come from in (in this case) ogg files? I realize that it may perhaps not a VLC question (as VLC just displays them) but perhaps
there's ``expertise'' in the crowd here to shed some light resp. direct me to the right direction....

Here's the question in more detail: I have some ``home-made'' ogg-files. Home-made in the sense that they don't have really a digital
origin, it's not a download. The files are orginally taped from radio (some evenl from FM radio and originally really taped on a magnetic tape :-), Later I transferred them to minidisc,
and finally I digitized them via audacity, for instance into ogg files.

Now, what spooks me: in quite some cases (but not all) VLC shows some moderately fitting thumbnail picture. Sometimes the resolution is rather coarse grained (as
if there's noise in the picture)

What puzzles me is: where does the picture come from? I doubt that the pictures can somehow be secretly have been hidden in the source, as the source sometimes
had been radio. I doubt that there is a "data base" of pictures that has been looked up to make the connection, as they are not popular music stuff, just some radio featues.

So: has it been injected into the oggs via tools like audacity (but then again: how)? Also that seems strange as I did the following: first I transferred the complete file (with differrent
features and potcast into digitized format. So that file contained different "topics" in one big audio file. Only afterwards I cut it up into individual ``podcasts'' like 30 minutes worth
of an ogg-file, and it's those pieces which are shown with a (sometimes) characteristic thumbnail.

Or is it VLC that figures out some fitting graphic? But again how? Perhaps it's even just based on the file name. As an example: I have a file "borgiapopes.ogg" which contains
an old radio feature about the Renaissance-popes from Florence and VLC shows the coat of arms of the those popes! Which tool was smart enough to show that or add that?

It spooks me :-)

Thanks, Martin

martinsteffen
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Re: ``spooky'' thumbnails in audio (ogg) files

Postby martinsteffen » 02 May 2017 08:54

an update: I had asked a corresponding question on an ``audacity forum'' as I suspected it was
potentially the digitalization via audacity that injected the thumbnail pictures.

I got an authoritative sounding answer that audacity never adds pics like that. That would leave the VLC player
which somehow figures out ``plausible images''. But if so, VLC is pretty smart. For instance, I have an old taped radio feature
about the Renaissance popes. It's in a file called borgiapaebste.ogg (as it's in German). Still, VLC shows as picture what seems to be a papal
coat-of-arms, which, if VLC figures that out, is more than a little impressive (and cannot be by coincidence).

Martin

zcot
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Re: ``spooky'' thumbnails in audio (ogg) files

Postby zcot » 04 May 2017 16:15

The art is retrieved with lua modules if you allow the network settings for it(which you have). There is a number of possible locations where the art might come from.
http://git.videolan.org/gitweb.cgi/vlc. ... fd;hb=HEAD


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